1. Field of the Invention
The present invention relates to high density semiconductor memory modules, and more particularly to a method of forming a multi-chip semiconductor memory module, and to the multi-chip semiconductor memory module so formed.
2. Prior Art
A substantial part of the cost of manufacturing computer systems directly depends upon the space occupied by the integrated circuit chips used to fabricate the systems. Thus it is important to minimize the size of semiconductor memory modules.
One structure to increase the chip density is formed by mounting or stacking chips on one another. Prior art, e.g., U.S. Pat. No. 4,423,468 shows examples of dual stacked chips to form a double-chip structure in which both chips are bonded to a single substrate. The active faces are directed away from each other to permit easy electrical connection to the exposed input/output (I/O) terminals on each chip.
JP-A-56-137665 describes a dual inline package module (DIP) containing two pairs of semiconductor chips, each chip having solder mounds on its active face for electrical connection to the circuits within the chips. The active faces of the chips of one pair are mounted facing each other with solder mounds on one chip aligned with corresponding solder mounds of the other chip. The two pairs are stacked by facing the back of the upper chip of the first pair with the back of the lower chip of the second pair.